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Low-temperature catalytic methane deep oxidation over sol-gel derived mesoporous hausmannite (Mn_(3)O_(4)) spherical particles

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ChemPhysMater 2024年第3期3卷 329-340页

作者： patrick Ndouka Ndouka Stephane Kenmoe Jacques Richard Mache Elie Acayanka Dick Hartmann Douma Ralph Gebauer patrick Mountapmbeme Kouotou department of Chemistry Faculty of SciencesUniversity of MarouaP.O.Box 814 MarouaCameroon department of Theoretical Chemistry University of Duisburg-EssenD-45141 EssenGermany department of Mining Engineering School of Geology and Mining EngineeringUniversity of NgaoundéréP.O.Box 115 MeigangaCameroon department of Inorganic Chemistry Faculty of ScienceUniversity of YaoundéIP.O.Box 812 YaoundéCameroon Groupe de Simulations Numériques en Magnétisme et Catalyse Facultédes Sciences et TechniquesUniversitéMarien NgouabiB.P.69 BrazzavilleCongo The Abdus Salam International Centre for Theoretical Physics(ICTP) 34151 TriesteItaly National Advanced School of Engineering of Maroua University of MarouaP.O.Box 46 MarouaCameroon Higher Institute of Agriculture WoodWater and EnvironmentUniversity of EbolowaP.O.Box 118 EbolowaCameroon

In this study,Mn_(3)O_(4) spherical particles(SPs)were synthesized by the sol-gel process,after which they were thermally annealed at 400℃,and comprehensively characterized.X-ray Diffraction(XRD)revealed that Mn_(3)O_(4) exhibited a tetragonal spinel structure,and Fourier transformed infrared(FTIR)spectroscopy identified surfaceadsorbed functional *** electron microscopy(SEM)and the specific surface area analyses by Brunauer−Emmett−Teller(BET)revealed a porous,homogeneous surface composed of strongly agglomerated spherical grains with an estimated average particle size of∼35 nm,which corresponded to a large specific surface area of∼81.5 m^(2)/g.X-ray photoelectron spectroscopy(XPS)analysis indicated that Mn_(3)O_(4) was composed of metallic cations(Mn^(4+),Mn_(3)+,and Mn^(2+))and oxygen species(O_(2)−,OH−and CO_(3)2−).The optical bandgap energy is∼2.55 *** of the catalytic performance of the Mn_(3)O_(4) SPs indicated T90 conversion of CH4 to CO_(2) and H2O at 398℃ for gas hourly space velocity(GHSV)of 72000 mL^(3) g^(−1) h^(−1).This observed performance can be attributed to the cooperative effects of the smallest spherical grain size with a mesoporous structure,which is responsible for the larger specific surface area and available surface-active oxygenated *** cooperative effect of the good reducibility,higher ratio of active species(OLat/OAds),and results of density functional theory(DFT)calculations suggested that the total oxidation of CH4 over the mesoporous Mn_(3)O_(4) SPs might take place via a two-term process in which both the Langmuir−Hinshelwood and mars−van Krevelen mechanisms are cooperatively involved.

关键词： Sol-gel Manganese oxide Catalytic oxidation Methane Langmuir−Hinshelwood mechanism mars−van Krevelen route Two−term process

In situ Fourier Transform Infrared Spectroscopy Diagnostic for Characterization and Performance Test of Catalysts

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Chinese Journal of Chemical Physics 2017年第5期30卷 513-520,I0001页

作者： patrick Mountapmbeme Kouotou 田振玉中国科学院工程热物理研究所北京100190 中国科学院大学北京100049 马鲁阿大学萨赫拉高等研究院喀麦隆

The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.

关键词： In situ Fourier transform infrared spectroscopy Diagnostic Thermal stability Redox property Catalytic mechanism

Anterograde and Retrograde Regulation of Nuclear Genes Encoding Mitochondrial Proteins during Growth, development, and Stress

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Molecular Plant 2014年第7期7卷 1075-1093页

作者： Sophia Ng Inge de Clercqc Olivier Van Akena Simon R. Lawd Aneta Ivanovad patrick Willems Estelle Giraud Frank Van Breusegem James Wheland ARC Centre of Excellence in Plant Energy Biology University of Western Australia Australia Joint Research Laboratory in Genomics and Nutriomics College of Life Sciences Zhejiang University Hangzhou 310058 RR. China department of Plant Systems Biology VIB and Department of Plant Biotechnology and Bioinformatics Ghent UniversityTechnologiepark 927 B-9052 Gent Belgium department of Botany ARC Centre of Excellence in Plant Energy Biology School of Life Science La Trobe University Bundoora 3086Victoria Australia department of Medical Protein Research and department of Biochemistry 9000 Ghent Belgium Present address: Illumina ANZ 1 International Court Scoresby Victoria 3179 Australia

Mitochondrial biogenesis and function in plants require the expression of over 1000 nuclear genes encoding mitochondrial proteins （NGEMPs）. The expression of these genes is regulated by tissue-specific, developmental, internal, and external stimuli that result in a dynamic organelle involved in both metabolic and a variety of signaling processes. Although the metabolic and biosynthetic machinery of mitochondria is relatively well understood, the factors that regu- late these processes and the various signaling pathways involved are only beginning to be identified at a molecular level. The molecular components of anterograde （nuclear to mitochondrial） and retrograde （mitochondrial to nuclear） signaling pathways that regulate the expression of NGEMPs interact with chloroplast-, growth-, and stress-signaling pathways in the cell at a variety of levels, with common components involved in transmission and execution of these signals. This positions mitochondria as important hubs for signaling in the cell, not only in direct signaling of mitochondrial function per se, but also in sensing and/or integrating a variety of other internal and external signals. This integrates and optimizes growth with energy metabolism and stress responses, which is required in both photosynthetic and non-photosynthetic cells.

关键词： mitochondria mitochondrial retrograde regulation (MRR) organellar crosstalk signaling.

A Record of Anthropogenic Effects on Sedimentation in the Manatee River, Florida

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Journal of Environmental Science and Engineering(B) 2014年第1期3卷 1-13页

作者： patrick Schwing Ashanti Johnson College of Marine Science University of South Florida Saint Petersburg 33701 Florida USA University of Texas at Arlington Arlington 76019 Texas USA

Increased sedimentation rates have been attributed to increased anthropogenic activity in watersheds throughout Florida and many parts of the world. The Manatee River, located on the west coast of Florida （USA）, like many other coastal watersheds, has experienced depletion in natural resources, increased nutrient loading, and increased pollution. LARs （linear accumulation rates） from watersheds throughout Florida suggest that anthropogenic activity increased bulk sedimentation by as much as 4-fold. The objective of this study was to construct a record of sedimentation and improve upon previous studies by determining individual sedimentary constituent mars （mass accumulation rates） based on short lived radioisotopes （2~~pb and 234Th） to characterize changes in sedimentation attributed to increased anthropogenic development. This study constructed records of sedimentary accumulation rates to compare pre-development records to the past 100 years of anthropogenic development and identified specific changes in sedimentation attributed to anthropogenic activity. Anthropogenic development increased deposition of terrigenous material into the river from 2-fold to I 0-fold （0.3-2.0 g/cm2/yr） over three periods：（1） predevelopment period （1900-1941）; （2） agricultural development period （1941-1970）; （3） urban development period （1970-2010）. The mobilization of this amount of terrigenous material has implications for effects on water quality and biological communities within the river.

关键词： Sedimentation lead-210 cesium-13 7 man induced effects Florida Tampa Bay.

Indicators of global sustainable sourcing as a set covering problem:an integrated approach to sustainability

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Ecosystem Health and Sustainability 2015年第2期1卷 12-20页

作者： patrick R.Huber Nathaniel P.Springer Allan D.Hollander V.Ryan Haden Sonja Brodt Thomas P.Tomich James F.Quinn Information Center for the Environment University of CaliforniaDavisCalifornia 95616 USA Agricultural Sustainability Institute University of CaliforniaDavisCalifornia 95616 USA

Sustainability describes a broad set of themes centered on current human uses of the planet’s *** multiple uses and users of the term have led to a proliferation of salient issues and associated *** present a new method to systematically link these issues and indicators under two conceptual frameworks of sustainability in order to enable quantitative *** demonstrate this approach with a specific use case focused on the global sourcing of agricultural *** use the optimization software Marxan in a novel way to develop minimum sets of indicators that provide maximum coverage of sustainability *** covering sets were identified and accumulation curves were developed to measure the contribution of each indicator in each set to overall issues *** greater detail in the assessment of each indicator would likely provide more effective sets of indicators,those that were generated provide optimism that this approach can bring better focus to sustainability assessments.

关键词： global sourcing indicators Marxan software minimum covering set optimization sustainability